analysis of the flexible pavement 1

[Lee1974]

Hi everyone,

How to analyze the flexible pavement subjected to a heavy-duty tracked vehicle load?

According to what I've found from the net, most of the related study are based upon the wheeled vehicles and traffic estimation. But the problem I encountered is One single tracked vehicle(the average preesure is around 400KPA) moving on 10cm-AC pavement.

Can I just use the elastic material to model the pavement and the subgrade then give a strip loading (with FLAC 2D)?
But even I can do so, how to determine if the pavement fail or not?

Please tell me where I can find useful reference or suggestions. Thanks for your time.

P.S. I'm from Taiwan. If I said something wrong, forgive my poor English.

 

[AegisFPE]

I do not have the information to solve your problem, but I think it will depend on the configuration of the track.

If the track has teeth ____/\_____/\_____/\_____/\_____ (pardon my simple sketch) I would anticipate that flexible pavement would not be suitable.

If the tracks are smooth, then it may be possible to calculate the appropriate thickness for the axle loads, but vehicle turning movements may still scar the pavement as the tracks scrape the surface.

 

[dik]

There are two programs available on the internet called EALF.xls and F806Beta2.xls that can be used for flexible pavements. I'm not sure of the application of loading except that tracked vehicles provide less loads than wheeled vehicles. As AegistFPE notes, the scuffing from turning operations is likely going to cause the most wear and tear.

Dik

 

[Ron]

Tracked vehicles must be analyzed by different methods than you would use for typical wheel loads.

I would use elastic layer analysis, setting the track loads at 12 inches apart, so that overlapping load analysis could be done. As an example, assume your load on the whole track is 40 kip and the track is 10 feet long. The load configuration would be 4 kips/ft with the load placed at every foot. I would then analyze 3 consecutive loads with the center load being the critical one.

If you are analyzing a concrete pavement, then look at lateral stress at the bottom of the concrete layer. This will equate to flexural stress in the concrete, which shouild be no more than 50% of the ultimate flexural strength of the concrete. If you are analyzing a flexible pavement, then look at two parameters....first look at the lateral strain at the bottom of the asphalt layer and look at the vertical strain at the top of the subgrade. You can look up the limits of each for your pavement.

Good luck.

 

[dik]

Ron: I don't know about flexible pavements, but loads on rigid pavements can have a radius of influence of 5 or 6 feet or more. Using 3 loads only provides for a 1' radius of influence and you might consider 5 or 7 loads.

 

[Lee1974]

Hi, everyone:

Thank you for all your replies.

I am planning to do a numeric analysis under the plane-strain condition(for conservative and convenient analysis), and the tracked-vehicle load will be modeled as two strip loads.

According to what Ron mentioned, I have to know the limit strength (or limit strain) of the asphalt concrete pavement(flexible pavement) in order to compare with working stress (working strain). But after days of searching for these AC characteristics, I found few articles about it, so could you please give me more information about it?

Thanks again.